An undetermined amount of potentially-contaminated products made with ground chuck were shipped to two dozen counties in Florida including Brevard, Citrus, Hillsborough, Sarasota and St. Lucie. They were purchased by consumers between June 25 and July 31, the USDA says. Publix has 788 stores in Florida and a total of 1,191 stores across the U.S.

An investigation began after 18 people, predominantly from Florida, became ill between July 5 and July 25, according to the USDA's Food Safety and Inspection Service. All consumed ground chuck products purchased at various Publix stores and supplied by an as yet undetermined source, the service says.

Sickness from this strain of E. coli usually happens two to eight days after exposure. Most people have vomiting and diarrhea (often bloody), the USDA says. Most people recover within a week, but in rare cases some may develop a more severe infection.

Consumers who have purchased these products and may have frozen them are urged not to consume them, the USDA says. These products should be thrown away or returned to the place of purchase.